Age structure diagrams can illustrate population growth rates by shape. Which statement below correctly describes this use?

Age structure diagrams can illustrate population growth rates by shape. Which statement below correctly describes this use?

• A. They display average annual rainfall
• B. They show genetic variation
• C. They can show population growth rates with their shape
• D. They show GDP per capita

Answer: (C)

Age structure diagrams show how a population is distributed by age and sex, and their shape reflects the growth rate. A broad base with many young people indicates high birth rates and rapid growth, a more uniform distribution across ages suggests slow or stable growth, and a narrow base with an aging population signals low birth rates and slow or negative growth. This is why the shape of the diagram is used to infer population growth rates. The other options don’t fit because age structure diagrams depict age and sex distribution, not rainfall, genetic variation, or economic indicators like GDP per capita. In practice, observing the pyramid’s shape also hints at future trends, since a large young cohort can drive continued growth as they enter reproductive age.

Age structure diagrams show how a population is distributed by age and sex, and their shape reflects the growth rate. A broad base with many young people indicates high birth rates and rapid growth, a more uniform distribution across ages suggests slow or stable growth, and a narrow base with an aging population signals low birth rates and slow or negative growth. This is why the shape of the diagram is used to infer population growth rates. The other options don’t fit because age structure diagrams depict age and sex distribution, not rainfall, genetic variation, or economic indicators like GDP per capita. In practice, observing the pyramid’s shape also hints at future trends, since a large young cohort can drive continued growth as they enter reproductive age.